DESCRIPTION: (Applicant's Description) The long term goal of the proposed research is to understand the mechanism by which AP-2 transcription factor regulates gene expression in breast cancer cells and to develop novel methods for early detection, prognosis and therapy for breast cancer. There are three specific aims: 1) to identify novel proteins that interact with AP-2, 2) to clone the genes of novel proteins that associate with AP-2, and 3) to determine how these proteins interact with AP-2 to regulate gene expression in breast cancer cells. AP-2 associated proteins will be identified by co-immunoprecipitation with antibodies against AP-2. Such proteins will be purified and sequenced. If they are already known, their roles in gene regulation will be investigated. If they are novel, then their genes will be cloned by reverse transcription and cDNA library screening. Their roles in the regulation of gene expression will be determined by mutation, reporter gene transfection assay, transfection with antisense plasmids, co-immunoprecipitation immunocytochemistry. The proposed research is important because AP-2 transcription factor is not only involved in normal development but also in several cancers including breast carcinoma, melanoma, teratocarcinoma, and possibly other cancers. More specifically, AP-2 is a regulator of c-erbB-2/HER2/neu which is an important diagnostic factor in breast cancer. The proposed research will be conducted using breast cancer cells because some of them express high level of AP-2 which will make it easier to isolate AP-2 associated proteins.